During the past year we have initiated studies to evaluate the various virologic and immunopathologic processes which occur when viruses replicate in the ocular microenvironment. This is a new project which is presently composed of three areas. (1) Evaluation of virus spread in HSV-1 induced retinitis. (2) Studies on coronavirus infection in ocular and optic nerve cells. (3) Possible role of viruses in human diseases. Retinitis following anterior chamber inoculation of herpes simplex virus (HSV-1) is an interesting model of viral spread and virus induced disease. During the past year we have elucidated some of the pathologic mechanisms involved in this disease. We found that footprints of the immune system (IFN-gamma and MHC class II antigen expression) can be identified in the protected retina strongly indicating that it is the immune which protects the retina from virus destruction. Moreover, we identified the virus in the ciliary body and ciliary nerves suggesting that this may be the mode of spread of the virus to the uninjected eye. Elucidation of virus spread and activation in the retina may provide insight into these same mechanisms in human disease, such as ARN. We have initiated studies to evaluate coronarvirus infections in the eye and optic nerve. Preliminary studies using monoclonal anti-virus receptor antibody has identified selected cells within the eye which express virus receptors. These studies will be extended to evaluate virus induced ocular damage.